In general, a heat exchanging apparatus provided to an apparatus for supplying hot water is to absorb combustion heat generated from a burner, and includes heat exchanging pipes through which water flows and heat transferring fins for absorbing the combustion heat, so as to heat water using the combustion heat in order to make hot water.
FIG. 1 is a schematic view showing the structure of a conventional gas powered boiler.
In a heat exchanging apparatus 1, heat energy generated by a burner 20 is transferred to a heat exchanger 10 including a first heat exchanging pipe 11a so as to heat water in the heat exchanger 10. The hot calefactory water is forcibly supplied to locations which require heating by a circulation pump (not shown), so as to transfer heat energy. At this time, a blower 30 is installed at a lower portion of the burner 20 in order to effectively transfer heat energy to the heat exchanger 10. Meanwhile, exhaust gas is discharged outside through a smoke tube 40.
The calefactory water circulated by the circulation pump transfers its heat to the locations which require heating, and then returns to the relatively cold water so as to be introduced through the inlet into the heat exchanger 1. This process is repeated, so that the calefactory water is continuously circulated.
In the gas powered boiler having the above mentioned structure, since water in a pipe for heating water rises in temperature and there occurs no temperature difference between external air and the heating water during the operation of the boiler, there occurs no condensate water at the inlet pipe 50 for the heat exchanger which is installed at an inlet port through which the heating water is introduced into the heat exchanging apparatus 1.
In the boiler having the above mentioned structure, when much time passes in the state that the operation of the boiler stops, all of pipes in the boiler, the heat exchanger, pipes connected from the boiler to rooms respectively, and pipes arranged in the rooms are fully filled with cool water of which temperature has dropped. Further, the temperature of water in the pipes for heating becomes lowered to level identical with temperature of air around the boiler.
When the boiler operates in a state that the temperature of the water in the heating pipe is low, there occurs temperature difference between the cool water in the heating pipe and the air heated by the combustion of the burner.
Such a temperature difference seriously occurs in winter when a temperature of water in heating pipes is very low. Moisture, which is contained in the atmosphere, is condensed on a peripheral surface of pipes of the heat exchanger, so as to be condensate water.
Since high temperature heat is directly transferred from the burner 20 to the heat exchanger 10 which includes a plurality of heat exchanging pipes installed therein, no water condenses on the heat exchanger. However, moisture contained in the atmosphere condenses on the peripheral surface of the inlet pipe 50 arranged at the inlet port of the heat exchanger through which the calefactory water is introduced, and the first heat exchanging pipe 11a because of the temperature difference between the cold water in the pipes and the external air. Such condensate water accelerates the corrosion of various parts, made of metal material, of the boiler.